Implementation of biocatalysis in continuous flow for the synthesis of small cyclic amines

Abstract

Significant progress has been made in establishing transaminases as robust biocatalysts for the green and scalable synthesis of a diverse range of chiral amines.[1] However, very few examples on the amination of small cyclic ketones have been reported.[2] Cyclic ketones are particularly challenging for transaminase enzymes because they do not display the well-defined small and large substituent areas that are characteristic for the biocatalytic mechanism. In this work, we exploited the broad substrate scope of the (S)-selective transaminase from Halomonas elongata (HeWT) to develop an efficient biocatalytic system in continuous flow to generate a range of small cyclic amines which feature very often in pharmaceuticals and agrochemicals.[3] Tetrahydrofuran-3-one and other challenging prochiral ketones were rapidly (5-45 min) transformed to their corresponding amines with excellent molar conversion (94-99%) and moderate to excellent ee.